1. Field of the Invention
This invention relates to the polymerization of butenes and, more particularly, this invention relates to the production of poly-n-butenes from a mixed C.sub.4 feedstream utilizing an aluminum chloride-hydrogen chloride co-catalyst system.
2. Description of the Prior Art
The production of isobutylene polymers from mixed C.sub.4 hydrocarbon feedstreams is generally known in the art . It is also known to utilize AlCl.sub.3 as the polymerization catalyst in such processes and the prior art discloses a number of co-catalyst or catalyst promoters, including hydrogen chloride for use under various conditions in isobutylene polymerization.
Representative disclosures include U.S. Pat. No. 2,957,930 which shows the use of 10 to 20% AlCl.sub.3 catalyst in the production of polyisobutylene from a C.sub.1 to C.sub.5 petroleum gas feedstock with 0.08 to 0.12 percent HCl, relative to AlCl.sub.3, used as a catalyst promoter. This reference notes that correspondingly small quantities of water vapor or chloroform, which can react with AlCl.sub.3 to release HCl, may also be used. British Patent No. 1,195,760 (1970) discloses the production of olefin polymers by polymerization in the presence of the catalyst comprising a liquid complex of AlCl.sub.3, HCl and an alkyl benzene. Polymerization products include materials other than polyisobutylene and products with a narrow molecular weight distribution are disclosed in this reference.
U.S. Pat. Nos. 3,200,169 and 3,200,170 deal with the reaction mixture separation methods after polymerization of propylene or butylene feeds utilizing an ammonia treatment process. HCl is disclosed in the references as a suitable catalyst promoter added to the reaction zone which contains an AlCl.sub.3 catalyst.
U.S. Pat. No. 3,997,129 discloses polybutylenes from a C.sub.1 to C.sub.5 liquefied refinery stream wherein the catalyst is solid particles of AlCl.sub.3 promoted with HCl gas or its equivalent. This process employs a static mixer for mixing catalysts and feed prior to conducting polymerization.
U.S. Pat. No. 3,985,822 relates to the production of poly-n-butenes by use of AlCl.sub.3 promoted with HCl but the objective is to reduce the isobutylene content of the polymer product.
U.S. Pat. No. 3,119,884 discloses a series of vertical column reactors useful for polymerizing isobutylene and further discloses a catalyst comprising AlCl.sub.3 and HCl or a substance which generates HCl. The catalyst system is described as an acid promoted AlCl.sub.3 catalyst. In such a system, a reaction between HCl and AlCl.sub.3 occurs to form H.sup.+ AlCl.sub.4.sup.- which is the species that initiates polymerization. According to this process, one method of introducing catalysts and reactants is to have the three materials, i.e., AlCl.sub.3, HCl and liquid feed, enter the reactor through the same duct. This necessarily results in polymerization beginning in the duct line in an exothermic reaction and the reaction is not controlled by the refrigeration system of the reactor. Any product formed under these conditions will have an undesirable low molecular weight and broad molecular weight distribution.
U.S. Pat. No. 3,501,551 is directed to a process for producing normal butene polymers at molecular weights of from about 200-750 wherein a C.sub.3-5 hydrocarbon mixture containing isobutylene and normal butylenes as substantially the only olefins present are reacted in liquid phase with an aluminum chloride catalyst to form a reaction mixture containing only isobutylene polymers. The isobutylene polymers are separated and thereafter the resulting reaction mixture is treated with a Friedel-Crafts catalyst to form a second reaction mixture containing normal butylene polymers. The aluminum chloride in the first polymerization section is indicated to be added alone or in combination with promoters, such as alkyl chloride, e.g., isopropyl chloride.
U.S. Pat. No. 3,639,661 relates to processes for polymerization of isobutylene employing as polymerization catalysts either a reaction product of titanium tetrafluoride with a chlorine bearing Friedel-Crafts catalyst which is soluble in isobutylene or a reaction product of titanium tetrachloride or boron trichloride with a fluorine bearing compound whose fluorine atoms are capable of partly replacing chlorine atoms in the titanium tetrachloride or boron tetrachloride. It is indicated that the catalyst can be made in situ by adding the catalyst components separately to the reaction medium.
U.S. Pat. No. 3,991,129 relates to the production of polybutene employing recycled reaction liquid, liquefied butenes and Friedel-Crafts catalyst, which is stated to be preferably aluminum chloride promoted with hydrochloric acid gas or its water equivalent. The catalyst is admixed with the recycle and fresh feed lines upstream of a static mixer prior to charging to the polymerization reaction column.
U.S. Pat. No. 4,465,887 relates to a process for producing butylene polymers having molecular weights of from about 400-5,000 wherein the feedstream containing mixed butenes is fractionated to remove recited amounts of cis-2-butene. The overhead fraction from the fractionating step contains isobutylene and is reacted in the presence of an aluminum chloride catalyst to polymerize the isobutylene and to form a reaction mixture consisting of isobutylene polymers and unreaction hydrocarbons including normal butenes. This reaction mixture is flashed distilled or recover the isobutylene polymers and the unreacted hydrocarbon mixture is then reacted in a presence of a catalyst system consisting of aluminum chloride and a promoter to polymerize butylenes in the fraction and form in a second reaction product mixture containing butylene polymers having lower molecule weights, e.g., of from 400-900 molecular weight. The patent indicates that a promoter is essential of a second polymerization reaction, and indicates that typical promoters are isopropyl chloride, t-butyl chloride, water and hydrogen chloride. The patent's promoters are added to the reactor separately from the aluminum chloride and the first hydrocarbon reaction mixture containing the unreacted normal butene.
U. S. Patent 4,558,170 relates to the preparation of polyisobutylene from a mixed C.sub.4 hydrocarbon feedstream containing at least about 6 wt % isobutylene using an AlCl.sub.3 - HCl catalyst system wherein the HCl is introduced separately into the feedstream to form organochlorides therein prior to introduction into the polymerization reactor.
U.K. Patent No. 1,449,840 describes a process for alkylating benzene, wherein benzene is contacted with a polybutene in the presence of aluminum chloride. The polybutene itself is prepared by polymerizing a mixed C.sub.4 feedstock containing from 2-20 wt. % of isobutene. The polybutenes are stated to be prepared by conventional polymerization process using a Friedel-Crafts catalyst such as aluminum chloride.
Belgium Patent No. 731,006 relates to the alkylation of aromatic hydrocarbons using n-butene polymers, wherein the polymers are produced from a refiner stream containing n-butene basically free from isobutylene which are polymerized in the presence of aluminum chloride.
European Patent No. 115,635 relates to a continuous process for producing polyisobutylene from isobutylene feeds, wherein solvents and monomer vaporized during the polymerization are recycled after liquefaction to the polymerization zone.